1. Field of the Invention
The present invention relates to fluid flow assemblies and, in particular, to tubular assemblies for pressurized fluid flow. More particularly, the present invention relates to an endform tubular assembly possessing reliable features for assessing the robustness of the endform tubular assembly in an automotive power steering system.
2. Discussion of Related Art
Power steering systems include a steering gear housing, a steering gear disposed in the steering gear housing, a pump for moving the power steering fluid under pressure, and a fluid flow bundle including a supply line for transporting pressurized fluid from the pump to the steering gear, and a return line for transporting the fluid from the steering gear back to the pump. Typically, such fluid flow bundles include one or more brackets or support members that are used to mount the power steering components within an automotive vehicle. The ends of the supply tube and the return tube may be individually connection to an inlet port and an outlet port in the housing, respectively, by employing means such as a “tube-o” connector wherein a threaded nut is used behind each of the tube-o connectors to secure each of the tubes to a corresponding threaded port in the housing. Tube-o connectors generally are considered to be inefficient since they require a separate installation step for each connection.
Other assemblies have been developed wherein a bracket is used to simultaneously couple a fluid supply line and a fluid return line in a fluid flow bundle using a single fastener wherein the complete system is connected to a housing with the torque of the single fastener. While the single torque bracket connection is effective for reducing the number of operational steps necessary in the assembling process, such assemblies are unsatisfactory because they generally require that at least one of the tubular members be brazed into a machined connector. Brazed connections are not reliable, particularly in applications where the brazed part is subjected to the harsh environmental conditions present in the engine compartment of an automotive vehicle. For example, the brazed part may be subjected to extremely cold temperatures in winter during periods when the automotive vehicle is not operating and then suddenly required to withstand high temperatures and pressures during operation of the automotive vehicle. Constant vibrational episodes and occasional debris entering the compartment also severely reduce the life expectancy of such brazed connections. Another disadvantage of prior brazed clamp plate connections is that the clamp plate does not sit flush against the housing, such that when torque is applied to the fastener, the bracket may distort leading to premature o-ring failure.
U.S. Pat. No. 7,032,500 describes a fluid flow bundle for a power steering system wherein both a pressure line and a fluid return line are simultaneously connected to a steering gear using a bracket requiring only a single fastener. The bracket includes an aperture through which the high pressure line extends and a U-shaped aperture configured to receive a return line assembly. The return line assembly includes a connector member to which the hose is brazed or welded. The connector member also includes a pair of circumferential flanges, which allows the U-shaped aperture in the bracket to swing over the connector member such that the return line assembly is secured to the bracket member between the pair of circumferential flanges. In such arrangement, the connector is compressed into the port to create a seal The high pressure tube is deformed to create a first bead and, after the high pressure line is inserted through the bracket, a second bead is formed to secure the high pressure tube to the bracket. Such arrangements are not without disadvantages. For example, the fluid flow bundle may employ undesirable brazing or welding for securing at least one of the supply line and the return line to the connector. Also two separate steps are needed to form the two beads on either side of the bracket for securing the non-brazed high pressure line to the bracket. Such arrangement is not only time consuming and labor intensive, but the supply line may be susceptible to undesirable axial rotation as well as up/down and side to side movement in the bracket. Such movements severely limit the life expectancy of the assembly. Furthermore, each of the return and pressure lines requires the additional step of forming a groove in the ends of the lines for receiving an o-ring. Consequentially, current tubular assembly design does not provide an economical fluid flow assembly having assured long term dependability and structural integrity, nor does it provide inherent features, which allow the reliable assessment of the robustness of such fluid, flow assembly.
Therefore, it would be desirable to provide a power steering assembly having a robust design exhibiting improved sealability, long term dependability and reduced manufacturing costs, and which has inherent computable quality control features for assessing the robustness of the endform tubular assembly and for predicting the performance of the endform tubular assembly in high pressure applications for prolonged periods of time.
3. Related Applications
The contents of copending applications U.S. Ser. No. 11/769,316, and U.S. Ser. No. 11/769,352, both relating to the same subject matter as the present application, and both of which are filed simultaneously herewith, are incorporated herein by reference thereto.